Coming Regulations May Downsize Tire Width, Too

Automakers are doing all they can to make cars lighter and more fuel efficient, as regulations for average fuel economy and permissible emissions grow ever tighter in Europe and the United States.

While automakers have downsized engines in the name of fuel economy and have trimmed weight wherever practical (and economically feasible), one component group in particular has gone in the opposite direction: wheels and tires.

Just a few decades back, a sixteen-inch wheel was cutting-edge in terms of performance, but today we see mainstream sedans hitting the market wearing 19-inch wheels shod with wide, low-profile tires. These may look good and offer better dry-weather traction, but they add weight, increase rolling resistance and up transmitted noise.

Upcoming European laws are expected to address both a tire’s rolling resistance and its generated noise. As Go Auto (via Green Car Reports) tells us, the only way to meet these new regulations will be with narrower tires mounted on taller wheels.

Before you worry about losing the size of the contact patch, tire makers have already considered this. As Pirelli’s Australian technical manager, Simon Pool, explains, “By making (tires) taller you can make the footprint narrow and long to keep it the same as the tires today.”

In other words, while the shape of the contact patch will change, its total surface area won’t change, at least not by much. To achieve this, expect wheels of the future to be some 21 inches in diameter, mounted with much skinnier tires.

The new tires are expected to deliver less noise, lower rolling resistance (of particular importance on electric cars) and better wet-weather braking, since the tires’ shape makes them more resistant to hydroplaning. They should be better in snow, too, since narrower tires are less prone to “float” atop the snow than wider tires.

We understand the science behind this, but still have a hard time believing a long and skinny contact patch offers the same lateral grip as a short and wide one, at least on dry pavement.

Can tread compounds improve to the point where this doesn’t matter? Will cars shed enough weight that wide tires aren’t needed for maximum grip in corners? For future track day fun, we hope the answer to both questions is yes.